Safety control switch



, Jan. 11, 1955 SOGGE 2,699,477

SAFETY CONTROL SWITCH Filed Dec. 2, 1953 INVENTOR. MELVIN s. soess ATTORNEY United States Patent 2,699,477 SAFETY CONTROL SWITCH Melvin G. Sogge, Los Angeles, Calif., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis,

' a corporation of Delaware Application December 2, 1953, Serial No. 395,793 6 Claims. (Cl. 200-87) directed to improvements in controls of the above mentioned type for use in heating systems in a conventional, manner.

One of the objects of this invention is to provide a very compact control which is particularly suitable for use in very confined spaces such as areusually found in space heater, floor furnace and Wall heater installations.

Another object of the invention is to provide a safety control which has a minimum number of parts, has a simple operating mechanism, and is of sturdy construction.

Still another object of the invention is to provide a relatively small control device which is inexpensive to manufacture and is of generally improved construction over prior art devices of the same general type.

Still other objects of the invention will become apparent upon reading the following detailed description of the invention in conjunction with the accompanying drawing wherein:

Figure 1 is a plan view of the safety control taken along line 1-1 of Figure 2;

Figure 2 is a side view of the control with portions thereof shown in cross section; and

Figure 3 is a cross sectional view takenalong line 3-3 of Figure 2.

The housing for the safety control includes a frame support, generally designated by the reference numeral 11, having a base portion 12, two end portions 13 and 14 and two side portions 15 and 16. The housing is completed by a cover member, generally designated by the reference numeral 17, which includes a top portion 18, two side portions 19 and 20 and end flanges 21 and 22. The cover 17 is retained on the frame 12 by means of a bolt 23 screw threaded into a threaded hole (not shown) in the wall 13.

Mounted on the inner surface of the base 12 of the support, is a switch subassembly generally designated by the reference numeral 24. It consists of a framework of insulating material, preferably Bakelite, which has an inverted cup-shaped chamber 25. The chamber is bounded by two side walls 26 and 27 and two end walls 28 and 29, and a top wall 30. Integral extensions 26a, 28a, and rib 31 on wall 30 provide separators for electrical wiring to be presently described. Also forming an integral part of the framework 24 are two spaced and parallel walls 32 and 33 having aligned bores 32a and 33a therein through which a pivot member 34 extends, for a purpose to be described hereinafter. The framework is secured to the base 12 by means of bolts 35 extending through holes in lugs 36 and 37 formed on the framework 24 as an integral portion thereof. The bolts 35 extend freely through the holes in the lugs and are screw threaded into threaded holes in inwardly struck portions 12a and 12b, respectively.

Coaxially arranged bores 38 and 39 extending through the walls 28 and 29, respectively, are substantially parallel with the base 12 and the sidewall 19 of the cover. Slidably mounted in these bores 38 and '39 is a stepped plunger 40 having a rounded and generally. rectangular v of the safety control, the parts will assume the "ice head portion 41 and a non-round or flattened reduced diameter portion 42. The portion which extends through the bore 38, which is larger than the bore 39, is round. The non-round portion 42, which slides in the bore 39, carries a contact bar 43 with a non-round hole 44 therein, which snugly fits around the plunger portion 42 so as to provide an axially slidable but non-rotatable connection therewith. A coiled compression spring 43 resiliently biases the contact bar 43 into engagement with the shoulder formed between the portions 40 and 42 of the plunger and both the bar and the plunger toward the wall 28. The head 41 of the plunger is prevented from rotating by means of two spaced vertically extending ribs 46 formed on an integral with the wall 28.

Two spaced terminal members, one on each side of the spacing rib 31, are generally designated by reference numerals 47. The terminal members comprise a head portion 48, which rests against the outer surface of the wall 30, and downwardly extending arms 49 that extend through slots 50 in the wall 30 and lie against the inner surfaces of the wall 28 on opposite sides of the plunger 40. The terminals 47 are retained in their assembled position by means of clasps 51 which extend through slots 52 and 50a formed in the wall 30 and are bent over at their inner ends into engagement with the inner surface of the wall 30. The heads 48 of the terminal members have threaded bores 53 therein which receive terminal screws 54. The screws 54 are adapted to clamp the ends of lead wires (not shown) from the control system in which the control device is used, which lead wires pass through the opening 55 formed in the end wall 13. It will thus be seen that a circuit may be completed through the unillustrated lead wires by means of the contact bar 43 bearing against the two spaced contact arms 49 under the bias of spring 45.

Mounted in the other end of the housing is a thermocouple energizable electromagnet and armature unit, generally designated by the reference numeral 56. It comprises a cylindrical housing 57 enclosing an electromagnet and an armature 59 cooperable therewith. A stem 60, on which the armature 59 is mounted, is axially slidable into and out of the housing 57 and is resiliently gilasled outwardly by means of a coiled compression spring of the stem 60. The retainer is held on the stem by means of a split ring 63 positioned in an annular groove in the stem 60. The thermocouple unit is held in its housing, with the plunger 60 in coaxial relationship with the contact plunger 40, by means of a threaded connector sleeve 64 extending through an opening 13a in the wall 13 and a clamping nut 65 screw threaded onto said sleeve, to rigidly clamp the wall 13 between the nut 65 and housing 57 of the electromagnet. Leads of a thermocouple (not shown), adapted to be heated by a pilot burner (not shown), are connected to the coil 58 of the electromagnet through the sleeve 64 and a contact rod (not shown) extending through the sleeve 64 and supporting the electromagnet in the housing 57, in a conventional manner.

Rotatably mounted on the pivot 34, which is held in place by its head 34a and a friction nut 34b, are two levers 66 and 67. The lever 66 is a solid lever having an outwardly bowed bearing portion 66a that bears against the rounded portion of the head 41 of the plunger 40, and bearing bosses 67d through which the pivot 34 extends. The lever 67 is formed of two flat plates having rounded portions 67a adapted to bear against the spring retainer 62 on opposite sides of the split ring 63 and which are integrally joined by means of cross bars 67b and 670. It will be noted that the lever 66 crosses the lever 67 by extending between the sides of the lever 67 and between the cross bars 67b and 67c, to provide a scissors-like action therebetween. The thickness of the levers 66 and 67 between the rounded outer surfaces of the portions 66a and 67a, is such that in the off position positions shown in Figure 2 of the drawing. That is, the spring 61 will hold the armature 59 in its retracted position, the lower end of lever 67 bearing against the lower end of lever 66, lever 66 hearing against the plunger 40, the head 41 ofthe plunger 40 bearing against the wall 28, and

caring against a spring retainer 62 on the outer end the contact bar 43 being held spaced from the contact arms 49, against the bias of spring 45.

As the electromagnet 58 is not sufficiently strong to attract the armature 59 thereto upon energization of the electromagnet by a thermocouple, manual means is provided for pivoting the lever 67 to move the armature 59 into engagement with the electromagnet while holding the lever 66 stationary, thus keeping the contact bar 43 out of engagement with the contact arms 49. This means takes the form of a disc 68 that is connected to the free end of a leaf spring 69 by means of a button-like connector 70. The disc 68 is secured to the connector 70 by means of a split ring 71 fitting in an annular groove in a reduced diameter portion of the connector 70, while the connector 70 is secured to the leaf spring 69 by another reduced diameter portion extending through a hole in the leaf spring and being riveted thereto. The leaf spring 69 has a downwardly bent and widened portion 69a that is secured to the wall 13 by means of rivets 72 extending through holes in the wall 13 and the portion 69a.

To provide easy manipulation of the disc 68, an inverted cup-shaped plastic button 73 is secured to the leaf spring 69 over the connector 70 by means of integral projecting pins 73a extending through holes (not shown) in the leaf spring 69 with a tight fit. The push button 73 extends through an opening 18a in the cover, while dirt is prevented from passing through the opening 18a by the spring 69 holding laterally extending flanges 73b on the button against the inner surface of the wall 18 around the opening 18a. If desired, a laterally-slidable sealing gasket may be positioned around the button 73 andl ligtween the flanges 73b and the inner surface of wal Operation With the above described safety control installed in a heating system, with the electromagnet connected to a thermocouple positioned to be heated by a pilot burner and with the terminals 48 connected to a main burner gas controller, the system may be put into operation by pressing inwardly on the button 73. This will bring the disc 68, which is swivelly mounted loosely on the connector 70 into engagement with the upper ends of the levers 66 and 67. Further inward movement of the disc 68 causes it to react against the lever 66 and rotate the lever 67 clockwise to move the armature 59 into engagement with the electromagnet. If the pilot burner is burning, the electromagnet will hold the armature and the releasing of button 73 will permit the spring 45 to rotate lever 66 clockwise about pivot 34 and to bias the contact bar 43 into engagement with the contact arms 49. It will be observed that due to the fact that the floating lever 68 is of disc shape, it is unnecessary to provide means to prevent rotation thereof, as it will engage levers 66 and 67 in all angular posi tions thereof.

The circuit to the control system for the main burner will remain completed through contacts 49 and bar 43 so long as the thermocouple is energizing the electromagnet, which means so long as there is a flame at the pilot burner. Upon flame failure, the armature is released and spring 61 will move levers 66 and 67 counterclockwise and contact bar 43 away from contacts 49, thus breaking the circuit to the main burner and causing safety shut down.

As modifications may be made in the above described preferred embodiment of my invention, without departing from the spirit thereof, the scope of the invention must be determined from the appended claims.

I claim as my invention:

1. In a safety control, the combination comprising a control slidable between on and off positions in a bore in a support, a condition responsive means having a plunger coaxial with said bore and movable between held and released positions, first and second levers pivoted intermediate their ends on a common pivot, one end of each of said levers being positioned between said plunger and control, means biasing said plunger against said first lever, said first lever against said second lever and said second lever against said control to normally hold said plunger in its retracted position and said control Ill) in its off position, a leaf spring fixed at one end and extending over the other ends of said levers, means on said spring for engaging said other ends when said spring is manually flexed toward said other ends to move said plunger to its held position and said control to its on position.

2. A safety control comprising a support, a control member movable generally rectilinearly on said support between on and off positions, means biasing said member towards its on position, condition responsive means on said support having an actuator movable between a held position and a released position and movable substantially rectilinearly in line with said control member, means biasing said actuator towards its released position, a pair of crossed levers pivoted intermediate their ends on a common pivot, one end of each of said levers being positioned between said actuator and said control member, a floating lever, a leaf-spring fixed at one end on said support and engaging the middle of said floating lever at its other end, said floating lever being positioned to engage the opposite ends of said pivoted levers upon. movement of said .floating .lever toward their common pivot.

3. In a safety device, the combination comprising a control movable between on and off positions, a condition responsive means having a plunger coaxial with said control and movable between held and released positions, first and second. levers pivoted intermediate their ends on a common pivot, one end of each of said levers being positioned between said plunger and control, means biasing said plunger against said first lever, said first lever against said second lever and said second lever against said control to normally hold said plunger in its retracted position and said control in its off position, a leaf spring fixed at one end and extending oversaid levers, means on said spring for engaging the other ends of said levers when said spring is manually flexed toward said other ends to move said plunger and control to their held and on positions, respectively.

4. A control device comprising a support, a control member movable generally rectilinearly on said support between on and off positions, means biasing said member towards its on position, condition responsive means on said support having an actuator movable between a held position and a released position and movable substantially rectilinearly in line with saidcontrol member, means biasing said actuator towards its released position, a pair of crossed levers pivoted. intermediate their ends on a common pivot, one end of each of said levers being positioned between said actuator and said control member, a floating lever positioned to engage the opposite ends of said pivoted levers upon movement of said floating lever toward their common pivot, and means for actuating said floating lever.

5. The combination comprising a control movable. substantially rectilinearly between on and 'off positions, a condition responsive means having a plunger coaxial with said control and movable substantially rectilinearly between held and released positions, first. and second levers pivoted intermediate their ends on a common pivot, one end of each of said levers being positioned between said plunger and control, means biasing said plunger against said first lever, said first lever against said second lever and said second lever against said control to normally hold said plunger in its retracted positionand. said control in its off position, actuating means fixed at one end and extending over the other ends of said levers, and means on said actuating means for engaging said other ends when said actuating means is manually moved toward said other ends to move said plunger to its held position and said control to its on" position.

6. A safety control comprising a support, a control membermovable generally rectilinearly on said support between on and off positions, means biasing said member towards its on position, condition responsive means on said support having an actuator movable between a held position and a released position and movable substantially rectilinearly in line with said control member, means biasing said actuator towards its released position, a pair of crossed levers pivoted intermediate their ends on a common pivot, one end of each of said levers being positioned between said actuator and said control member, an actuator secured at one end on said support and loosely secured to the middle of a floating lever in the form ofva disc at. itsiother end, said 'fioatingxlever being positionedmto engage the opposite ends of said pivoted levers upon movement of said floating lever toward their common pivot for moving said control to its on position.

References Cited in the file of this patent UNITED STATES PATENTS Re Qua. June 30, 1925 

